Tuesday, 5 December 2017

LED Escape Lights - Repurposing

My two boys have, for their play 'crib', a large shed. But this time of year they get little use from it, because its dark.

It just so happens though, that Ive acquired a pair of LED Emergency Escape Lights - the sort of thing you see over fire exits. Now, these are supposed to sit there, connected to the mains, keeping an internal battery charged, until such time as the mains fails, and then they illuminate for 30mins, to provide a guide for anyone attempting to escape a dark and possibly smoke filled building.

The pair Ive obtained each have an array of 27 5mm white LEDs, along with the charging and control circuit board and a 3.9v 1500mAh NiCd battery.


 Immediately, the possibility of converting these into 12v 'penthouse' lamps comes to mind. A 12v system is safe enough that I can let the boys have full control over it - so long as the supply is secure. In this case, the supply will be a large Sealed Lead Acid Battery, so all thats needed is a box.

The LEDs are arranged in parallel groups of three, each group with a 1ohm current limit resistor, on a single long PCB strip. The majority of the main PCB in each lamp is the mains switch mode inverter and battery charger circuit.


Most of the mainboards circuitry is therefore of no use for the new application. The only part that is, is the small black device in the center of the photo below



This is a 7135 Low Drop Out constant current regulator. Its job, is to provide a fixed 350mA drive to the LEDs. This works out at around 13mA per LED at 3v.

There is one problem though - the 7135 has a maximum input voltage of 6v! So, a further regulator, or other voltage dropping technique, is still required to bring the 12v supply down to within the 3-6v range of the 7135. Luckily, the industry standard 7805 1A 5v regulator, is incredibly cheap, and I likely have several in stock.



On each blog post  I will be including the following link -
 £50 credit if you switch energy supplier to Bulb Ltd
This is my own personal referral link, not an advert! I am with Bulb for gas and electricity. Do your own research, but if you decide to switch to them, do so via the above link, and we both get a £50 credit!

Saturday, 25 November 2017

Control and Programming Software for the ubc125xlt

One of the things ive found playing with my new toy, is that controlling it is not exactly the most intuitive process! It does take a bit of getting to grips with, and the manual, although not Chinglish, is far from straightforward or well laid out.

Direct entry of a frequency, and its storing in memory, is not as simple as my venerable MVT-7100, but then, the Yupiteru doesnt do alpha-tagging to allow naming of stored channels. So the entry of more than a couple of frequencies is rather tedious and tiresome.

Luckily, a chap by the name of Nick Bailey has created a Visual Basic program to program and control the scanner from a PC.


Scan125 is the programs name, and it can be obtained from http://www.nick-bailey.co.uk/scan125/ 

Its takes a little time to find your way around, but its certainly much easier than direct entry! Especially as the entire scan banks can be edited on the PC, handy when first setting up with a lot of channels to enter!

Two things with it though, first, you must follow the instructions to set up the driver for the scanner properly. Its simple but different! Second, a splash screen will annoy you every 10mins if you dont register the software. Registration is easy but he does do it by a rather odd method involving a lot of clicking of mouse buttons.

For many people, especially those who are new to the use of scanning receivers, the big problem they have is finding something to listen to! Here, I would always suggest to start with the VHF Airband, as there are always signals there. Beyond that, many people give up quickly due to not finding anything to listen to, as the patience required seems to be beyond many. To this end, I would advise at first start up to chuck the PMR446 and UK 'Simple' Business radio frequencies in. These are very widely used due to the low licensing costs (free for PMR446 and £75 every half-decade for Simple).

Those coming to the hobby with a view to listening to the emergency services or mobile phones (as per the good old days!) - FORGET IT!!!


On each blog post  I will be including the following link -
 £50 credit if you switch energy supplier to Bulb Ltd
This is my own personal referral link, not an advert! I am with Bulb for gas and electricity. Do your own research, but if you decide to switch to them, do so via the above link, and we both get a £50 credit!

New Toys

As my main interest in general utility listening is more geared towards intercept and identification rather than content, I decided I would finally treat myself to a bit of new kit. I looked at the cost of DMR and dPMR capable scanners, but they are still very much out of my range, and besides, SDR is in many ways a more fitting system for such modes.

So I dropped on a Uniden Bearcat UB125XLT handheld scanner, 2nd hand for a good price. The attraction of this device is Uniden's 'Close Call' feature - a strong signal intercept mode.

The above of course is a stock photo (the giveaway is the model number which has clearly been over-typed! I suspect the original photo was of the US market 125AT version!).

One very useful modification that can be made to scanners is to provide a high impedance raw audio tap from the discriminator. This is very easy to do on the 125 as the headphone output connector is stereo but the unit of course mono - giving an available connection. It just requires the removal of the L- and R- balance resistor, and the addition of a 10k resistor and wire between the discriminator and the audio socket. Rather conveniently, all the important signal paths in this receiver have nice big test points!


 All the photos above show the receiver in various states of dismantlement. The photo of interest is the one bottom right, this is the RF board. The big chip to the left of the IF filter (the big cream block on the lower right) is the IF subsystem IC, to the left of this is a large test pad for the discriminator output, marked DISC. At the top of the board between the BNC socket and the volume pot, can be seen the 3.5mm stereo jack socket. Just below that the balance resistor.

Later today I will perform the discriminator mod. But only once my workshop has warmed up!

On each blog post  I will be including the following link -
 £50 credit if you switch energy supplier to Bulb Ltd
This is my own personal referral link, not an advert! I am with Bulb for gas and electricity. Do your own research, but if you decide to switch to them, do so via the above link, and we both get a £50 credit!

Wednesday, 15 November 2017

Software Defined Radio and Pager Decoding

Ive been playing again recently with my cheap R820T RTL dongles. These, when used with suitable custom drivers and SDR software, are interesting devices allowing for the reception of all manner of signals.

In this case, ive been using mine with the SDRsharp software package to control them (referred to as SDR#), and playing with attempts to receive and decode digital audio and trunked network signals. Ive not had much luck that way yet, but what I have had success with are pager signals.

Some of you reading this (I suspect most of my readers!) will be old enough to remember the period in the mid 1980s to the early 90s when mobile phones were the size of a housebrick, public payphones either vandalised or used as conveniences, and the alternative to a landline the very short lived Rabbit DECT system!

During this telecommunications chaos, those who wished to look like Yuppies but without the budget for a phone, carried a pager. My mate Ian had one - I dont actually recall it ever beeping! ;-) Most people think these legacy devices are obsolete with the coming of GSM phones, but no, they still exist, now used mostly for alerting on-call staff, sending telemetry messages, and are also now a valuable part of the emergency services response systems.

These devices live on the VHF bands around 138MHz and 153MHz. Two protocols are still in general use - POCSAG (Post Office Code Standards Advisory Group) and FLEX, at several baud rates from 512 and 1200 (POCSAG) to 1600 and 3200 (FLEX)

By combining SDR# with a software package called PDW, these signals can be decoded into their numeric or alphanumeric messages.


There are many users of these systems, and it seems different channels carry generally different traffic. The frequency in use in the image above is 153.275MHz. This is a 1200bd POCSAG signal, with timing/test messages (not decodable) every minute. When there is message traffic, it is generally numeric or simple tone alerting. Likewise its apparent sister frequency 153.250MHz. To the right in the waterfall can be seen 153.325MHz (3600bd FLEX) which seems to carry a lot of machinery telemetry and general 'call so and so' messages, and 153.350MHz, 1200bd POCSAG (CH3), which for me is the easiest and generally busiest frequency. To the left of the waterfall can be seen another FLEX channel, 153.025MHz, this also transmits a very regular timing pulse, as can be seen.

For anyone trying the above software combination, I have found that the following settings work for me - RTL gain 38dB (adjust this on yours to get signal peaks around 30dB above the noise), receiver bandwidth 15kHz, SDR# audio out 54dB.

I have spent quite some time exploring the 153MHz channels, so now will move down to 138MHz and try my hand at decoding those.

On a related note, ive taken the plunge today and purchased a Uniden UBC-125xlt handheld scanner. This isnt to replace my venerable Yupiteru MVT-7100, but instead to add to my capabilities with its 'close call' features. Ive also ordered another R820T2 SDR dongle, and a pair of MCX to BNC pigtail cables, as I intend enclosing the dongles into aluminium boxes to help cut down the noise floor.

Tuesday, 7 November 2017

A Plug for Bulb...

My energy supplier (electricity and gas) is Bulb Ltd. They run a referral program for new customers.
The link below ive provided for anyone who is considering switching energy suppliers, to take a look and do your own research into them. Take a look at their reviews online as well.

https://bulb.co.uk/

So, your thinking, all well and good, but how does that help your readers save money?

Well, its simple - If you sign up to change your supplier to them, using a link that I will provide below, they give you a £50 initial credit! And, whats even better - they give me one as well!

Heres the link -

bulb.co.uk/refer/martin7906

Numbers Stations

Many years ago, at the height of the Cold War (mid 1980s - not the mid '60s as the press would have it!) , I used to listen to strange broadcasts consisting of spoken groups of numbers. Much later I discovered these 'numbers' stations, existed all over the world, and were government run covert stations, transmitting operational orders to 'agents in place', what the thriller writers would call spies.

Since the fall of the Berlin Wall, these stations have much decreased in number and activity - but they do still exist!

This morning, I have been listening to one named E11 (these names come from the CONET project, that documented these stations), on 7317kHz USB.

The original Enigma and CONET projects no longer exist, however there is still a group that is documenting these stations -

http://priyom.org/

One great aspect of this projects website, is that on the homepage there is a schedule and a 'next station' timer! This makes tuning these stations in very easy - simply tune to the frequency and mode shown for the 'next station' and wait...

Sunday, 15 October 2017

All the UKs frequencies on Google Earth?

Yesterday, someone pointed out to me that it was possible to download the whole of Ofcoms license allocation database, as a comma separated variable delimited file. This is the list of who holds what licenses for what specific frequencies, not amateur licenses, or users of license free channels.

This info of course is of great interest to scanner users, but the original .csv file rocks up at over 70MB and around a third of a million entries!

Now, wouldnt such a file, showing who is using what frequencies and where, be great on Google Earth?

Glutton for punishment that I am, and recognized at work as the Google Earth Gnome, I foolishly set about trying to convert a 70MB .csv file into a workable set of .kmz files!

Key to this, are three steps - First, remove all non-geographical entries. These are frequencies and users allocated on a nationwide basis, and hence have no position information for Google Earth to work with. Second, remove all duplicates. In this case, a duplicate entry is one where the same user, is listed with the same frequency, in the same location. A frequency can be used by the same user in a different location, thats a valid entry, as is a different user using the same frequency, etc. And third, split the file into manageable chunks.

The first two operations have been done using the data handling tools in Microsoft Excel. The third needed some thinking about. I opted to split the file into separate files based on area, and chose to use the Ordnance Survey 100km gridsquares


Most areas, this creates an easily handled file size. The exception is grid TQ, which covers that there London. The density of allocations in London is such that I have had to split that file into four, and perhaps even more, based on frequency band.

The resulting .csv files, can be imported direct into Google Earth. Ultimately, I wish to convert them to .kmz files that are native to Google Earth and can be distributed, such that any user can just open the file and it will work. Imported .csv files require some setting up.


The above pic is a screenshot of my Google Earth Pro with three of the gridsquare files imported and enabled.

Tuesday, 10 October 2017

Can my blog save you money?

Quite possibly!

Just recently, I received an email from British Gas, my energy supplier at the time. This email informed me that my gas and electricity bills were not only going to go up by a extortionate amount, but also that they were ending the dual fuel discount as well. The general gist of the email was "pay up or sod off"...


... so I sodded off!

After a lot of research, trawling comparison sites and the like, I narrowed down a number of new suppliers, which were smaller, much cheaper, and it seemed more ethical than British Gas. And out of these, one caught my eye - Bulb.

Bit of a gimmicky name for an electricity supplier! But, the more I read, the more I liked what I was reading. Committed to customer service, committed to renewable energy sources, and online open forum for customers and non-customers alike. So, after looking at my potential savings, I signed up with them.

The link below ive provided for anyone who is considering switching suppliers, to take a look and do your own research into them. Take a look at their reviews online as well.

https://bulb.co.uk/

This was just over a month ago, and ive just submitted my second set of meter readings. All seems to be going very well so far, and any queries ive had have been dealt with by their team via the forums swiftly. So far im happy with them and alls going well. Im on a list for the trial of next generation smart meters as well. The only odd part is that payments are done initially by debit card, but you can call and set up a direct debit (I must remember to do this!), and also, they work on an advance payment system, which means you actually pay up front, and if you overpay either it holds on your account or you can ask for it rebated. This seems very odd at first, but in many ways it does make sense.

So, your thinking, all well and good, but how does that help your readers save money?

Well, its simple - If you sign up to change your supplier to them, using a link that I will provide below, they give you a £50 initial credit! And, whats even better - they give me one as well!

Heres the link -

bulb.co.uk/refer/martin7906

I would suggest this - If your considering changing your energy supplier - go and research Bulb online, also research other suppliers, and find the one that is right for you. IF, you find that Bulb suits you, then use my link above to get yourself, and me, fifty quid!

Im not going to try to convince you, coerce you, or force you! But, it makes sense to me to take up an offer if your switching anyway, so my referral link is there above for you, should you choose to use it.

Clear as mud

Well, for some reason, the plum wine isnt clearing. Wine making has taken up pretty much most of my spare time recently, and shortly some beer brewing will also join my activities, now I have a nice big fermentation bucket!

Thats not to say there is no radio planned! Due to workload, and my walking mate Bob M1BBVs change of career, walking and field radio have been rather sparse. However, hopefully soon (next few weeks) we will be back out there. A few rail trail walks and some long outstanding SOTA is on the horizon!


Anyway, back to the wine! It would seem the problem here is a protein or pectin haze. As this wine has already has two-part finings (isinglas/gelatine and keiselsol) ive decided to try another electropositive fining agent,  this time Bentonite, which is known for its ability to drag proteins out of suspension. Its a bit more faffy to use than other finings, as the extremely hygroscopic particles of this volcanic clay must be hydrated into a slurry prior to use.

But, it does also give me a chance to exchange the airlock and bung fitted, with a solid bung, freeing up the airlock for other use. Hopefully now this wine will clear over the next couple of days, and can then be bottled - which will free up the demijohn for racking off one of the other wines!

Monday, 2 October 2017

Variant "WOW" wine

Ive not been on here much lately, mostly due to work and the like, but that doesnt mean ive not been busy,

I have, just not with radio!

Instead, Ive been wine making. This is something I always intended to to do, but never got around to, despite my experiences of it as a kid helping the chap over the road.

But it occurs to me that my blogs are a good place to record experiments in this line. To date ive completed and drunk a 5L kit Cabernet Sauvignon, I have an apple wine, using my own fruit, bottled. A plum, again using my home grown fruit, in the process of clearing. I have a kit chardonnay bubbling away in early secondary, and a strawberry getting close to the end of fermentation.

This morning, I decided to quickly throw on a "WOW" variant. Now, WOW stands for Wurzels Orange Wine, and in its pure form of course uses oranges. A 'variant' generally refers to a wine made using store bought juices. This is what I have gone for.

This will be an Apple, Watermelon and Raspberry wine. No messing about with hydrometers for this one! Just 3L of 100% juice and 1100g total sugars.

Heres the recipe -

1L 100% red grape juice
2L 100% apple, watermelon and raspberry juice*
820g granulated sugar
1L water
1 cup strong tea (tannin)
1/2 tsp Pectolase
1 tsp glycerine
2 tbsp lemon juice (acid)

*1L in must, 1L in fridge for topping up

A general purpose wine yeast, activated in a  cup of warm water with 2 tsp sugar, was the first thing to get started. After that, the demijohn, airlock and other needed kit was sterilized. Luckily these days, with everyone so health conscious, cartons of juice have the sugar content printed on them. So, I knew I had 308g of sugars in the juice, so needed to add around 808g. With the variability of scales, I probably put 820g in. I didnt mix the sugar well enough with the 1L extra water, so have just had to spend 5mins swirling the must to dissolve the excess. With all the additives, sugar, water and first two juices in, theres a bit over 3L of must, coming to just below the shoulder of the demijohn. The lemon juice provides the acidity, whilst the strong cup of tea provides the tannins. A bit of glycerine to improve mouth feel, and some pectolase enzyme to help break down any fruit pectins.

I pitched the yeast once everything else was in, and when checked this afternoon (about 6 hours later) it was bubbling at about four every minute. So, after getting all the extra sugar dissolved, ive now transferred the demijohn to my usual 'production line', where it can now stand and crack on with primary fermentation. As WOW wines can often become somewhat 'lively', this one is stood in a drip tray!

Once its done with primary, maybe three days or so once it gets properly started, i'll top it up with the remaining juice. This wine should complete secondary in under two weeks, and once cleared should be drinkable more or less straight away.